The Sword of Rhiannon

Matt Carse, explorer of interplanetary ruins, was very interested when he was informed by a small-time thief that the fabulous Sword of Rhiannon had been found. Rhiannon was one of the ancient gods of Mars, who had used his powers for evil and had been eternally consigned to damnation by the Science Lords of that wonderful epoch. The superstitious Martians would not venture into the cave where the spirit of Rhiannon was said to be, but Matt, being an Earthman, did not share their fears.

But ...